Superfluid flow provides a coupling of zero sound to the real squashing modes in **3He-B that is different from the particle-hole asymmetry (pha) coupling predicted by Koch and Woelfle. This superflow coupling is calculated in the BCS plus Fermi liquid theory and is shown to have a different angular dependent attenuation spectrum than the pha//3coupling. The order of magnitude of this coupling is determined by v//s and known properties of **3He and should be observable at flow velocities well below the critical flow velocity.